This invention relates to improved flux gate magnetometer or compass units for giving indications of directional orientation relative to an ambient magnetic field, normally the earth's field.
The flux gate devices of the present invention are of a known general type in which a core structure or core means of paramagnetic material are alternately driven magnetically in opposite directions and beyond saturation by an alternating current. The core means are also positioned to be in the earth's magnetic field and magnetically biased by that field. Associated flux gate coil means flux linked to the core means are operable in response to variations in saturation of the core means to produce an electrical output representing the directional orientation of the coil means relative to the earth's field. One prior art patent showing a flux gate arrangement of this general type is my prior U.S. Pat. No. 3,888,201 issued June 10, 1975 on "Auto-Pilot". In the arrangement of that Patent, the core takes the form of a ring of paramagnetic material having coils wound thereabout at different circularly offset locations.
In such flux gate devices, the magnetic bias provided by the earth's magnetic field causes two core portions associated with oppositely wound coils to become saturated at different times by reason of the presence of the earth's field. This differential saturation then causes development of an output signal representing the directional orientation of the unit relative to the earth's field. In my U.S. Pat. No. 3,888,201, there are four flux gate coils offset ninety degrees from one another and connected into a bridge circuit for producing the electrical output signal. It has also been proposed heretofore that separate input and output coils be utilized in conjunction with such a ring magnetometer, with the ouput coils being wound diametrically about the entire ring, in two mutually perpendicular planes. A ring core magnetometer of this type is described in a report commencing on page 7.1-1 of the "1965 Proceedings of the Intermag Conference, International Conference on Magnetics, Washington, D.C., U.S.A., Apr. 21, 22, 23, 1965", published by the Institute of Electrical and Electronic Engineers, Inc.
In instances in which a flux gate device of the described type may be employed as a compass element for a boat, aircraft, or the like, as in the auto-pilot of my U.S. Pat. No. 3,888,201, it may be necessary to mount the wound core, by gimbals or the like, for universal leveling movement relative to the rest of the device, to thereby always maintain a proper level orientation with respect to the horizontal, and thus assure development of an accurate directional indication. One disadvantage of such an arrangement, however, is that the electrical leads which are connected to the windings on the core may tend to interfere with and resist leveling movement of the core, or may eventually break or be damaged by the flexure occurring such movement.